Gas burner control system



J. C. BOGLE GAS BURNER CONTROL SYSTEM Original Filed March 2l. 19?7 April 12, 1932.

the boilerv or furnace.

Patented Apr. 12, 1932` f UNITED STATES A.PATENT- ori-Ica JOHN C. BOGIE, OF RIVER FOREST, ILLINOIS, ASSIGi-NOB, BYTMESNE ASSIGNMENTS, T0

MINNEAPOLIS-HONEYWELL REGULATOR COMPANY, OF

A CORPORATION F DELAWARE MINNEAPoLr-s, MINNESOTA,

GAS BURNER CONTROL SYSTE'.

Original application Serial No. 176,859, led March 21, 1927. Divided and this application led December 11, 1928. Serial N0. 325,172. Renewed April 9, 1931.

This application is a division of application Ser. N o. 176,859 filed Mar. 21, 1927 for gas burner control system by the applicant of this application.

This invention relates to a control system for gas burners and has special reference to a safety control system for a gas-fired boiler,

substantially even temperature, to Aprovideaperiodic supply or demand, or any other instance wherein gas `is permitted to ow to a i burner latf intervals.

Automatic heating systems are equipped with controls responsive to variations of teniperature in a room or other enclosure to be heated; for example, such a control may comprise -a wallthermostat capable of directing the generation of heat 'for assuring against substantial variations in the room temperature. Other forms of controls for automatic heating systems are those directing the speciic limits vof temperature to be obtained in These latter instruments may include a water thermostat 0n a hot water heating boiler, a pressure switch on a stem or vapor boiler, or an'A air thermostat upon a warm air furnace.

Any of the above enumerated controls, or several thereof, may be so arranged in the present system as to govern the sequence of operation of the various devices in order that gas may b e fed to the burners when desirable. In order to avoid complications of the drawings and disclosure, the several embodiments' of this invention are primarily controlled by a simple room thermostat.

This invention is further enhanced by safety controls which operate to shut down the system in the event of failure of those controls previously recited to 'promote or sustain desirablel conditions of combustion within the boiler or furnace. a

. Moreover, in order to illustrate the further tion has been incorporated in an automatic vheating system wherein the burner is supplied with a mixture of gas and air under pressure.

Other objects will be apparent from the description and the drawings forming a part of this specification to which reference may now be had for a more complete understanding of the characteristic features of this invention, in which drawings:

Figure 1 is a more or less diagrammatic view of a gas burner control system in- /corporating an arrangement whereby the burner is supplied with a mixture of gas and air under pressure; and

Fig. 2 is a verticalsectionalwview of the ignition device in the control system.

Referring more particularly to the draw ings, the control system comprises a re ducing valve 10 which 'is directly connected to the main supply of gas 11. Itis usual for gas t'o be supplied for domestic use at about six to eight ounces of pressure. The reduc- \ing. valve 10 reduces-this line pressure to any desired pressure, in this instance to about two ounces, which latter pressure is substantially constant. ATheV 'gas under re duced pressure is directed to the lower chamber of a relay or snap valve 12` through a conduit 13, and thence to the main burner 14 through a conduit 15. AIn order that a mixture of gas and air under pressure in the burner be obtained, this system incorporates line to mix with the gas. In order to accomplish this result an ordinary gas and air ,mixer 16 is disposed in the conduit 15 and receives a supply of air under pressure from any source of supply such as a fan 17 oper-V ated by anelectric motor 18. After the gas v passes through the gas and air mixer 16 it is directed to the burner 14.

The gas from the reducing valve 10 to the /l' chamber of the snap valve 12 to shutoff the supply of gas to the main burner when the switch 19 closes the valve 20 and the pressure being reduced in the snap valve 12 to permit lmeans for forcing air unto the gas supply a flow of gas to the burner 14 by means of the thermostatic switch 19 opening the valve 20. A portion of the gas leaving the reducing valve is by-passed to the upper chamber of the snap -valve 12 through conduits 21,` 22, and 23, a throttling valve 24 being positioned between conduits 21 and 22. The magnetic valve is connected to a T-fitting throu h conduit 25 and communicates with conduits 21 and 22.

The various devices of the control system will now be specifically described whereafter their operation in the system will be related. The reducing valve 10 is of the usual type having upper and lower chambers separated by means of a diaphragm 26, said diaphragm having a valve 27 secured thereto and extending into the lower chamber to seat a ainst a suitable valve seat 28. An adjusta le screw 29 is provided in the upper chamber for asserting a, proper pressure upon the diaphragm 26 so that any desired pressure may be obtained within the lower chamber. It is desirable, although not essential to the operation vof the system, to provide such a reducing valve since the pressure in the main line isnot always constant and a considerable quantity of gas is withdrawn at certain times; for example, during meal times, and lesser quantities at other times.

The electromagnetically operated valve 20- comprises a base member 30 which is drilled.

to provide inletand outlet ports and valve chambers. The conduit25 enters the inlet p ort formed at one side ofthe base 30, while a conduit 31v is connected to the outlet port formed in the opposite side and below said inlet port. A main port 32 connects `the inlet and outlet openings, the port 32 being controlled by t e movement of .an iron lunger 33 which is vertically reciprocable in an upstanding tubular member 34, which latter is suitably secured to the metal base member 30 and rises substantially centrally therefrom, as shown. A coil spring 35 is secured between the top of the tubular portion 34 and the upper end of the plunger 33 whereby the lunger is maintained in position to close t e main port 32 when the valve is de-energized. The tubular portion 34 comprises an electromagnetic coil of the usual construction. In the operation of tliis device the coil is energized and the electromagnetic lines thread through the plunger 21, and the latter is raised against the action of the spring 23 whereby the degree of opening of the main port 20 is controlled.-

A more thorough understanding of the construction and operation of this valve may be had by reference to a copending application liled November 27, 1925, bearing Serial No. 71,860.

v The magnetic coil is electrically connected lto the room thermostatically operated switch 19 which controls the energization and deenergization of the electro-magnetic coil. The room switch 19 may be of any usual type but for the purpose of a specific illustration and means for a better understanding, the device has been shown in the drawings as comprising a mounting base of a suitable insulating material to which is secured a bracket 36 having a downwardly extending portion 37. A thermostatic element 38 of an expansible and contractible bellows type is supported by an extension 39 mounted on the insulating base. The other side of the bellows contacts with an actuating arm member 40 which latter occupies a substantially vertical position and is pivoted at its lower end to the insulating base. The upper end of the arm 40 is adjustably connected by means of a link 41 to the lower extension of the bracket 37, which bracket suitably supports a mercury contactor tube 42 of the usual type having a body of mercury and a pair of spaced cooperating electrodes 'disposed therein.

The bracket 36 is tiltably mounted on the insulating base and is actuated into its various positions by means of the bellows 38 which latter is provided with a highly volatile fluid, thus rendering the bellows sensitive to the slightest temperature change. The bellows 38 either contract or expand to move arm 40, which latter being linked to the extension 37 causes the mercury tube to tilt in positions whereby the mercury contacter will be caused either to bridge the electrodes and to close the electrical circuit therethrough or toflow in the opposite direction wherein the electrical circuit is opened.

For a better understanding of the elements of this device and the operation of the same, reference may be had to a co-pending application, Serial No. 739.006 filed September 22, 1924, vand assigned to mv assignee.

The relay or snap valve 12 comprises upper and lower chambers separated by means of a diaphragm 43, the diaphragm in turn having mounted thereon a valve stem and head 44 for engagement with a valve seat provided at the inlet for thegas from the snap va'lve 10. In

.the operation of the snap valve 12 and when the desired pressure is obtained in the upper chamber, this pressure will force the diaphragm to seat the valve and to shut oi the supply of gas from the conduit 13 to the burner. When there is no pressure in the upper chamber, or the pressure therein is reduced suiliciently, the diaphragm permits the valve member to unseat and to cause a flow of gas through the conduit 13 intoy the lower chamber, and thence to the burner.

In the operation of the system thus far described, when the room in which the thermostatically controlled member 19 is positioned, has reached a pre-determined temperature, the change vin temperature will cause the bellows 38 to tilt the contacter tube to a osition wherein the mercury will bridge t e elecregulated that when the magnetic valve 20 is open more gas is capable of passing through the latter than can escape through the throttling valve; therefore, .thepressure built upv in the upper chamber of the snap valve 12 is reduced to open the valve and to permit a low of gas to the burner 14.

The gas to theburner is ignited by a pilot light 45 and after a predetermined interval, that is, when sufficient heat has been obtained in the boiler, Aa stack switch 46 is actuated to complete a circuit through the motor 18 which in turn operates the fan 17 to cause air to mix with the gas in the conduit, Because of the time elapsingbetween the operation of the stack switch 46 and the thermostatic switch 19, gas entering the burner is allowed a sufficient time to be ignited. However,upon the opening of the electrical circuit'in the room' thermostat switch l19, the magnetic valve 20 will become fle-energized at the same time in which the circuit is broken through the motor 18.

The stack switch 46 comprises a helical bi-metallicA element 47 disposed adjacent the end of the tube 48. and in axial alignment therewith.' One end of the helical bi-metallic element is secured to the tube 48 and the other end, is secured to a rod 49 extending,

through both the tubing anda casing on which the tube 48 is mounted. A mercury tubev contactor 50 having a pair of electrodes and a body of-mercury disposed therein is mounted on the end of the rod 49. In'the operation of the stack switch, when the helical bi-metallic element 47 is heated, one end thereof being fixed to the stationary tube 48, the other end being free will rotate to cause a rotation of the rod 49 which in turn tilts the contactor 50 and causes the mercury ysource of supply. is connected to one of the electrodes of the room thermostatic switch 19, the other electrode being connected to one side of the electromagnetically controlled A valve 2O andone of the electrodes of the contactor of the stack switch 46. The other side of the valve20 is connected to the other side of the line and the other electrode of the contactor 50 is connected through the motor ,18 to the last mentioned side of the line, thus both the valve 20 and the stack switch 46 are connected in series with the switch 19.

When an electrical vcircuit is completed' through the room switch 19 the valve 20 is opened to relieve the pressure in the upper chamber of the snap valve 12 and thereby to permit a supply of gas through the lower chamber of the snap valve 12 to the burner where it is ignited. The hot gases from the f operation of the motor and shuts olf the gas to the burner simultaneously, in the manner prevlously described.

Referring now to Fig. 2` of the drawings, the outlet conduit 31 from the magnetic valve 2O is connected to the safety pilot 45 which latter will now be described. The safety pilot comprises an elongated tubular member 51 having an aperture 52 at its upper end through which gas is permitted to escape in order to ignite the main burner 14. Gas is supplied through conduit 53 to the lower port-ion of the tubular member 51, said tubu lar member being of arelatively high coeiciency of expansion. A spring member 54 is suitably attached at one of its ends to the tubular member 51 and is perforated to permit the tube member 51 to pass therethrough. The free end of the spring member 54 extends at right angles to the tubular member and has secured at its outer end a valve stem 58 which latter projects downwardly through a packing gland to a point adjacent a seat 55 in a valve housing 56.

`The valve stem 58 has a lower co-eiiiciency of expansion than that of the tubular member 51. Theconduit 31 is connected to the valve 56 at a point below the seat 55. Conduit 57 .is connected to the valve housing 56 at a point above the seat 55 and communicates with the port provided between the valve stem 58 is normally open as the pilot light 55 is constantly ignited.. Heat proceeding from the flame which emerges from the pilot port will cause the tubular member 51 to expand more than the valve stem, thereby providing a spaced relation between it and itsseat; however, should the pilot light be extinguished the tubular member 51 will contract faster and to a greater degree than the valve stem 58, thereby causing the latter to seat and shut od the supply of gas through the conduit 31. rihis is the eect which it ordinarily produces by reason of the room lot \ thermostat 19 operating to close theimagnetic valve 20, the magnetic valve, of course, building up a pressure in the upper chamber of the snap valve 12 to cut off the supply of gas through conduits 13 and 15 to the burner 14.

It is to be understood that a plurality of safety pilots may be employed to operate a plurality of burners and that these pilots may be arranged in series one with the other 1Q whereby the failure of any or all pilots may result in the complete termination of the control system. This invention then is not to be limited to the specific structure shown and described since various modiiications of the system may be known to those skilled in the art without departing from the spirit and scope of this invention, and, therefore, the same is to be limited only by the scope of the appended claims and by the prior art.

20 I claim:

1. A control system for a boiler or furnacel having a burner for receiving a mixture of gas and air under pressure comprising a valve, a main gas supply, a gas pressure operated device supplied with gas from the main supply and controlling said valve, thermostatically vcontrolled means for controlling the amount of pressure in said device to regulate the supply of gas from said main supply to said burner, and a thermally operated switch connected in series with said thermostatically controlled means and actuated by the heat from said burner for controlling the supply of air to said burner.

2. control system for a boiler or furnace having a burner for receiving a mixture of gas and air under pressure comprising a valve v having chambers therein, onerof said charnbers being connected to said gas burner and being supplied with gas from the main supply, electrically operated means for con trolling they amount of pressure in the other of said chambers to regulate the supply of gas from said iirst mentioned chamber to said the energization of saidelectrically operated means, and a thermally operated switch connected in series with said main control switch and actuated by the heat from said burner for controlling the supply of air to said burner.

3. A control system for a boiler or furnace having a burner for receiving a mixture of fuel and air under pressure, comprising4 means for controlling the admission offuel to the burner in accordance with requirements for the operation thereof, ignition means for igniting the fuelsupplied to the burner, means for supplying air to the burner under pressure for combustion purposes, and

means responsive to the establishment of combustion at the burner for' bringing said air l supplying means into operation.

4. A control system for a boiler or furnace 05 having a burner for receiving a mixture Aof burner, a main control switch for controlling y fuel and air under pressure, comprising thermostatic means responsive to the tem erature of the space to be heated for control 'ng the supply of fuel to the burner, ignition means for igniting the fuel supplied to the burner, means for supplying air under pressure to the burner for combustion purposes, and .thermostatic means influenced 'by the heat generated at the burner for bringing said air supplying means into operation upon' establishment of combustion at the burner, 5. A control system for a boiler or furnace having a burner for receiving a mixture of gas and air under pressure, comprising a gas supply conduit extending to the burner, a valve in said conduit, a gas pressure operated device for controlling said valve, a connection from said gas supply conduit to said device, means governed in accordance with the output requirements of the burner for controlling the gas pressure in said device, ignition means for igniting the gas supplied to the burner, means for supplying air under pressure to the burner for combustion purposes, and means responsive to the establishment of combustion at the burner for bringing said air supplying means into operation. 5. A control system for a boiler or furnace having a burner for receiving a mixture of fuel and air under pressure, comprising a 95 fuel supply conduit extending to the burner, electrically operated means for controlling the flow of fuel through said conduit, a main control switch for controlling the energization of said electrically operated means, igni- 100 tion means for'igniting the fuel supplied to the burner, electrically operated means for supplying air under pressure to the burner for combustion purposes, a thermostatic device influenced by the heat generated by com- 105 bustion of fuel at the burner, and a switch actuated by said thermostatic device for .effecting energization of said last-mentioned electrically operated means upon establishment of such combustion.

lfn witness whereof l have hereunto subscribed my name. u

.i JOHN G. BOGLE., 

